The general goal of this proposal is to gain insight into the cell biologic events occurring in intestinal mucosa which permit rapid recovery from intestinal injury. The specific goal of this proposal is to utilize an in vitro model of intestinal epithelial injury that was recently developed by the Principal Investigator to better understand how epithelial cells shouldering a small epithelial denudation can rapidly establish epithelial continuity. The specific aims of this proposal are to: (1) pursue our recent findings that suggest the dependence of epithelial restitution on synthesis of basement membrane collagens under conditions in which the subepithelial matrix composition is substantially altered. Such restitutive conditions are characteristic of at naturally occurring in vivo erosive disease states; (2) assess the role of cell surface receptors for matrix components in regulating behavior and cytoskeletal arrangement of migrating epithelial cells and to pursue the mechanisms by which receptor-ligand attachment sites are severed; (3) examine the fate of polarized membrane in cells shouldering epithelial wounds; and (4) determine the matrix requirements of primary isolated intestinal epithelial cells for adhesion and to correlate these findings with integrins expression and distribution and to cytoskeletal organization. For these studies in vitro electrophysiological Using chamber techniques, in vitro cell adhesion assays, light and electron microscopy, in situ hybridization techniques, fluorescent immunohistochemistry, ultrastructural immunolocalization, and radiolabeled extracellular tracer molecules will be used to accomplish these goals. These studies should not only yield significant insights into epithelial cell-matrix interactions in response to an epithelial defect, but should also enhance our understanding of the fate of important cell surface molecules during migration of these cells in a physiologically relevant state such as epithelial wound healing. Finally, these studies on epithelial wound healing in native intestine have broad application to the many natural intestinal disease states such as viral enteritis, erosive enteritis, celiac sprue and acute intestinal mucosal ischemia, in which a favorable outcome is dependent on mechanisms that enable rapid epithelial repair -- the focus of this proposal.